Bug 1486798 - Do not connect/disconnect when selecting the same page again;r=daisuke

Differential Revision: https://phabricator.services.mozilla.com/D4455

--HG--
extra : moz-landing-system : lando

devtools/client/aboutdebugging-new/src/actions/ui.js

@@ -14,6 +14,12 @@ const Actions = require("./index");
 
 function selectPage(page) {
   return async (dispatch, getState) => {
+    const currentPage = getState().ui.selectedPage;
+    if (page === currentPage) {
+      // Nothing to dispatch if the page is the same as the current page.
+      return;
+    }
+
     dispatch({ type: PAGE_SELECTED, page });
 
     if (page === PAGES.THIS_FIREFOX) {

devtools/client/aboutdebugging-new/src/reducers/ui-state.js

@@ -13,7 +13,7 @@ const {
 function UiState(locations = []) {
   return {
     networkLocations: locations,
-    selectedPage: PAGES.THIS_FIREFOX,
+    selectedPage: null,
   };
 }